Portable computing devices and portable electronics devices are becoming increasingly more common place. Users of those devices expect more and more information to be displayed on a display carried by the device. For example, cell phones, Personal Digital Assistants (PDA's), a cell phone/PDA combination, hand held remote controls for TV's, stereo systems, digital cameras, digital video recorders, and global positioning system (GPS) receivers, are examples of electronic devices that possess state of the art image displays such as color Liquid Crystal Displays (LCD). One challenge presented by any display is the ability to easily manipulate information displayed on the display and to effectuate an action based on what type of information is displayed. For example, the execution of a program by touching a stylus to an icon on the display. For electronic devices with a touch-sensitive display that is operative to receive commands and execute actions based on touching the screen with a stylus, a user must first grab hold of the stylus by either unsnapping it from a clip or removing the stylus from a slot in which the stylus is stored when it is not needed.
One disadvantage of having to remove the stylus is that in some situations it is inefficient from an ergonomic standpoint for the user to use the stylus on the touch-sensitive display for certain functions, such as scrolling the screen up and down or left and right.
As one example, if a map displayed on a touch-sensitive screen of a PDA is too large to be displayed in its entirety on the screen, then the user must remove the stylus and then use the left/right and/or up/down scroll bars to move the image of the map around on the screen to see various portions of the map that are off-screen. Similarly, when joy sticks, cursor pads, track balls, or the like are used, they typically require movement of a cursor to position the cursor over the scroll bars followed by pressing another button that allows the scroll bar to be moved with the motion of the cursor. Alternatively, a scroll wheel that is moved back and forth by a finger of the user is used to move the scroll bar, but usually, only the vertical scroll bar is moved by the scroll wheel.
In FIGS. 1a and 1b, a prior electronic device 200 includes a housing 202, a touch-sensitive screen 211, a power switch 204, and a stylus 201 having a tip 203 for touching the screen 211. The stylus 201 is carried by the electronic device 200 and is stored in a slot 231 (see FIG. 2a) and withdrawn Wd when needed. The electronic device 200 also includes a cursor pad 210 for selecting icons 215 or other information displayed on the screen 211 and one or more function buttons 208. Other icons such as 213 for opening a list of programs or 206 for closing a program can be displayed on the screen 211 and can be activated by touching the tip 203 of the stylus to the icon. For purposes of illustration, the prior electronic device 200 depicted is typical of a PDA, but the prior electronic device 200 can be any electronic device in which a stylus is used to manipulate information displayed on a touch sensitive screen.
In FIGS. 2a through 2b, other features of the electronic device 200 can include a slot 231 for storing the cursor 201, an accessory port 235 for devices such as memory cards or other peripherals, a headphone jack 237 for listening to audio information via headphones, a cover 215 for protecting the screen 211 when not in use, and a port 241 for docking the electronic device 200 to a cradle, a docking station, a keyboard, or the like, and a reset button 243.
Because the screen 211 has a limited area dictated by its portable use, all of the information in an image memory (not shown) cannot be displayed in its entirety on the screen 211. For instance, in FIGS. 1a and 1b, icons 217 are not fully on the screen 211, while other icons 215 are displayed in their entirety on the screen 211.
Accordingly, the stylus 201 is often used to scroll the images on the screen 211 such that the icons 217 can be brought into full view on the screen 211. A vertical scroll bar 221 can be touched by the stylus 201 to scroll the images up or down on the screen 211 as indicated by a pair of up/down arrows 223. In some cases, the up/down arrows 223 can also be touched by the stylus 211 to scroll the images up or down. Similarly, a horizontal scroll bar 225 can be touched by the stylus 201 to scroll the images left or right on the screen 211 as indicated by a pair of left/right arrows 227. In some cases, the left/right arrows 227 can also be touched by the stylus 211 to scroll the images left or right. A finger of a user (not shown) may also be used to accomplish some or all of the same functions as the stylus 211 by touching a tip of the finger to the screen 211.
Alternatively, the cursor pad 210 or a track ball 212 (see FIG. 1b) can be used to move a cursor 219 across the screen 211 to select the scroll bars or arrows (221, 223, 225, 227) to scroll the screen 211. Typically, another control such as one of the function buttons 208 or track ball buttons 214 must be pressed while manipulating the track ball 212 or cursor pad 210 in order to effectuate a scrolling of the screen 211.
Because the ergonomic needs of a users will vary, the above mentioned pointing devices are not optimal for every user under all conditions of use. Therefore, the above mentioned pointing devices can have several disadvantages for some users.
The disadvantages to using the track ball 212 include its sensitivity to vibrations that can cause the users hand and/or finger to be jarred by the vibrations (particularly in mobile applications) resulting in inaccurate pointing. Moreover, two hands are usually required to accomplish a task using the track ball 212, one hand to hold the electronic device 200 and another hand to manipulate the track ball 212. Additionally, for drag-and-drop operations, usually one of the function buttons 208 or the track ball buttons 214 must be pressed. As a result, two hands are required and often two fingers are also required. The use of the buttons (208, 214) may require the user to focus on those buttons in order to activate them, thus distracting the user from the information being displayed on the screen 211. The track ball 212 and the buttons (208, 214) are also difficult to use when gloves are worn by the user.
The disadvantages of using a finger (not shown) as a pointing device on the screen 211 include finger prints can be smeared on the screen 211, the view of the screen 211 is obscured by the users fingers or hand, input resolution is low especially if the users fingers are large, drag-and-drop operations require the use of two hands, many touch-sensitive screens 211 may not respond to pointing inputs if the user is wearing gloves, and the finger can not be used as a pointing device when the cover 251 covers the touch-sensitive screen 211.
The disadvantages to the buttons (208, 214) include the user can make mistakes with respect to selection of the proper button, the buttons may be two small for the fingers of some users, the buttons may not be easy to discern from one another by tactile feel, size, or shape, the buttons may not provide sufficient tactile feedback to signal successful activation, and buttons are hard to activate if gloves are worn by the user.
A disadvantage of the scroll wheel 200t is that only one of the scroll bars (221, 225) can be scrolled by the scroll wheel 200t. Usually it is the vertical scroll bar 221. Therefore, if it is desired to scroll an image left and right, the scroll wheel 200t will have to be abandoned in favor of the stylus 201 or the user must configure the electronic device 200 via a software menu to scroll an image left and right using the scroll wheel 200t. 
Disadvantages of a joystick (not shown), or miniature joysticks such as the TrackPoint® by IBM®, the AccuPoint® as used in Toshiba® laptops, and other isometric joysticks/pointing devices are that they can be less useful if the electronic device 200 is to be used in a vertical orientation, they can be hard to control accurately if gloves are used or the users fingers are too large, they are not ergonomically efficient for all users and are not often positioned for manipulation by a users thumb, often two hands are required to use the isometric joystick, and in many cases the isometric joystick only moves the cursor but does not allow for selection of an action without the use of another control button.
Finally, the disadvantages to using the tip 203 of the stylus 201 include the stylus 201 must be removed from its slot 231 which can result in the stylus 201 being lost or misplaced, the stylus 201 can be hard to use when gloves are worn, two hands are needed to easily use the stylus 201, the stylus 201 is typically placed on a right hand side of the electronic device 200 so that the ergonomic needs of left hand users are not met by a right hand side placement of the stylus 201, and the stylus 201 can not be used as a pointing device when the cover 251 is over the touch-sensitive screen 211 because the tip 203 is prevented from touching the screen 211.
Therefore, there exists a need for a pointing device that can serve multiple functions and can be used to manipulate information displayed on a display while positioned in a slot or the like that stores the pointing device. There is also a need for a pointing device that allows information displayed on a display to be manipulated when the display is covered by a transparent cover or the like. Finally, there exists a need for a pointing device that is flexible enough to accommodate the ergonomic needs of a variety of users.